reserve n,m,k for Nat,
  x,X for set,
  A for Subset of X,
  A1,A2 for SetSequence of X;

theorem Th61:
  lim_inf A1 \/ lim_inf A2 c= lim_inf (A1 (\/) A2)
proof
  (A1 (\/) A2).n = A1.n \/ A2.n by Def2;
  hence thesis by KURATO_0:12;
end;
